Tool and method for cutting a hollow profile

ABSTRACT

A tool for cutting a hollow profile is designed both for cutting a flange on the hollow profile and for forming the hollow profile using an internal high pressure forming process. The tool has at least one cutting device which extends parallel to the longitudinal extent of the hollow profile, has a cutting edge and is displaceable transversely to the hollow profile. A side of the cutting device that faces the hollow profile is designed as a shaping die wall, against which the hollow profile bears at least during the internal high pressure forming. In addition, the tool my have an integrated embossing punch and also a perorating punch formed coaxially thereto, thereby also enabling optional embossing and/or perforating of the hollow profile in addition to the cutting and the internal high pressure forming.

This application is a National Phase of PCT/EP2004/011454, filed Oct. 13, 2004, which claims the priority of German patent document DE 103 50 156.8, filed Oct. 28, 2003, the disclosure of which is expressly incorporated by reference herein.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a method and apparatus for cutting a hollow body.

German patent document DE 197 24 037 C2 discloses such a method and apparatus, which uses mechanical cutting of a flange on the hollow body along a first cutting edge and internal high pressure cutting along a second cutting edge. The fact that the hollow body is deformed according to the internal high pressure forming process is utilized to the effect that the hollow body is severed transversely to its longitudinal extent preferably after internal high pressure forming has already been performed. During internal high pressure forming, a side of a cutting device which faces the hollow body is used for cutting the flange, and serves as a die wall, against which the hollow body bears during the internal high pressure forming.

A device or a method of this type is based on the general idea of designing a tool both for cutting a flange on a hollow profile and for forming the hollow profile according to the internal high pressure forming process. The tool has at least one cutting device which is displaceable in the transverse direction of the hollow profile and runs parallel to its longitudinal extent. A side of the cutting device facing the hollow profile is designed as a shaping die wall, against which the hollow profile bears after the cutting operation and during the internal high pressure forming following the cutting operation.

With a cutting edge formed on the cutting device, the tool therefore at least partly cuts off a flange, running in the longitudinal direction of the hollow profile, parallel to the longitudinal direction by displacing the cutting edge in the transverse direction of the hollow profile. After the flange has been cut off, the side of the device which faces the hollow profile is utilized as a shaping die wall, whose outer side bears against the hollow profile during the internal high pressure forming. In this case, the tool makes it possible to complete a cutting operation on the hollow profile blank, before the internal high pressure forming operation starts.

This type of construction or procedure therefore offers the advantage that two method steps, namely the cutting of the flange and the subsequent internal high pressure forming, can be effected in one production step using a single tool, thereby simplifying and streamlining the production process, which helps to achieve time or cost advantages.

German patent document DE 100 30 882 A1 discloses a precision cutting method and apparatus. In first embossing step, a punching strip is supported against a fixed surface by means of at least one hold-down, and the part which is to be fabricated is pressed at the same time or with a time delay into an embossing die, preferably against the spring force of a spring base. In the process, a sliding surface is produced on the lateral surfaces of the part. Following the embossing step, in a parting step, the punching strip is supported on a fixed surface by at least one hold-down and then the finished part is cut out with a parting punch in a parting die.

German patent document DE 199 01 304 A1 discloses a method of processing workpieces, in which essentially vertically moving processing tools which act on the work pieces are arranged at least one station and essentially horizontally moving processing tools are arranged at least one further station. At least two workpieces, preferably arranged axially symmetrically to one another with a clearance space between them are processed simultaneously in each station. In addition, a device suitable for carrying out the method is also disclosed. The device, which is designed as a press tool for example, makes it possible to perform cutting/perforating operations, after the deep drawing of a sheet-metal workpiece, on spatially differently oriented surfaces of the workpiece, thereby increasing the capacity of the device.

German patent document DE 40 35 938 A1 discloses a press tool with multiple movements, having a punch and die which are movable relative to one another due to the movement of the punch. Arranged opposite the punch inside the die is a counter punch which can be moved independently and with a variable force via hydraulic cylinders accommodated in the tool. In addition, a counter die, which may be arranged opposite the die, adjacent to the punch in the tool, is movable, independently and with a variable force via hydraulic cylinders accommodated in the tool. It is crucial in this case that the counter punch can be moved as part of the tool independently therefrom and with any desired and adjustable force, a factor which defines an additional movement. This counter punch is part of the tool, so a tool with multiple movements is now produced by the additional movement.

German patent document DE 101 36 792 A1 discloses a tool for trimming drawn parts.

An object of the present invention is to provide an improved method and an apparatus of the type described above, which can achieve a simplified production process can be achieved.

This and other objects and advantages are achieved by the method and apparatus according to the invention includes a positioning device which improves both the quality and reproducibility of the cutting operation and the forming operation. The degree of automation of the cutting and forming operation is also increased.

According to one embodiment of the invention, the tool has a bottom die and a top die which are displaceable relative to one another. In this case, either the cutting device is integrated into one of the dies, such that the cutting edge then forms an integral part of the respective die, or the cutting edge is designed as a separate component and fastened to one of the dies in a fixed position. Alternatively, the cutting device may be arranged on one of the dies in such a way as to have an adjustable stroke.

The described variations of the arrangement of the cutting device on the tool evidence the wide range of possibilities that the invention opens up with regard to process-optimized arrangement of the cutting devices. For example, designing the cutting device as a separate component which is fastened to one of the dies in a fixed position offers the advantage that, after a relatively large number of cutting operations, the cutting device or the cutting edge can be exchanged simply and quickly and thus the maintenance cost of the tool can be reduced. If the cutting device is arranged on one of the dies in such a way as to have an adjustable stroke, a markedly smoother mode of operation of the tool is obtained on account of the lower weight of the cutting device that must be moved, compared with the top or bottom die. On the other hand, the integration of the cutting device into one of the dies or the design of the cutting edge as an integral component offers the advantage that an especially precise and powerful cutting operation can be achieved. Due to the many possible ways of arranging the cutting devices on one of the dies, the invention makes it possible to react in a flexible manner to the most varied requirements with regard to the material and/or workpiece to be processed.

According to a preferred embodiment of the invention, at least one hold-down, which is provided in the region of the cutting edge fixes the flange of the hollow profile at least during the cutting operation. In combination with a positioning device which, before and during the cutting and forming operation, presses the hollow profile against the side of the cutting device which faces the hollow profile, such a hold-down ensures that the hollow profile is held in a fixed position during the cutting operation and thus ensures an exact cut of high quality. In addition, the hold-down provides for always identical positioning of the hollow profile inside the tool, so that a highly reproducible dimensional accuracy, and thus uniformity of the hollow profiles to be produced, are achieved.

An embossing punch may also be provided displaceable transversely to the longitudinal extent of the hollow profile. In this way, it becomes possible to make an embossment on the outside of the hollow profile after the forming operation. In addition to a cutting and internal high pressure forming operation, the invention thus offers the advantage of carrying out an embossing operation virtually simultaneously, but in particular without a tool change, so that a further production step with the tool according to the invention can be integrated in the respective work station. The embossing punch may be arranged in such a way that it crosses and passes through the cutting device in a corresponding opening during the embossing operation. In this manner, the embossing punch embosses an outer side (bearing against the die wall of the cutting device) of the hollow profile against the internal high pressure, a factor which leads to especially exact and dimensionally accurate embossing.

According to a further advantageous feature of the invention, at least one perforating punch, which is provided coaxially in the embossing punch, perforates the hollow profile after the embossing operation has been completed. According to this embodiment, in addition to cutting, internal high pressure forming, and embossing, perforation can now also be integrated as a further processing step in the same tool, as a result of which time and cost advantages are again obtained. In addition, the invention ensures high accuracy in the position and shape of the holes produced by the perforating punch, and thus the quality of the hollow profiles produced can be markedly increased. Compared with previous production methods in which the holes are made subsequently in the already finish-shaped hollow profiles, subsequent deformation (and thus dimensional inaccuracy) of the hollow profile can be avoided. Even in the opposite case, in which embossing is performed after the production of the holes, the invention offers the great advantage that the embossing punch does not adversely affect the dimensional accuracy (position and shape) of the holes produced by the embossing. In principle, with the tool according to the invention, first perforating and then embossing can be carried out after the internal high pressure forming, or vice versa.

It goes without saying that the abovementioned features and the features still to be explained below can be used not only in the respectively specified combination but also in other combinations or on their own without departing from the scope of the present invention.

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

In the figures of the drawings, identical reference numerals are used to designate identical, functionally identical or similar components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross section through a tool according to the invention with inserted hollow profile, before the cutting or forming operation;

FIG. 2 shows an illustration as in FIG. 1, but with actuated positioning device;

FIG. 3 shows a cross section through the tool according to the invention, after the cutting and forming operation and before the embossing or perforating operation;

FIG. 4 shows an illustration as in FIG. 3 but with embossing and perforating operation completed; and

FIG. 5 shows a cross section through the tool with opened top and bottom die.

DETAILED DESCRIPTION OF THE DRAWINGS

As shown in FIG. 1, according to the invention a tool 1 for cutting a flange 3 on a hollow profile 2, has a bottom die 7 and a top die 8, which are displaceable relative to one another. As seen in FIGS. 1 to 5, the top die 8 is displaceable toward the bottom die 7. (In general, however, it is also possible for the bottom die 7 to be displaceable toward the top die 8 or for both to be mounted in an displaceable manner.)

To cut the flange 3 on the hollow profile 2, the tool 1 has at least one cutting device 4, which runs parallel to the longitudinal extent of the hollow profile, has a cutting edge 5 and is displaceable transversely relative to the hollow profile 2. The cutting device 4 may be integrated in one of the dies 7 or 8, so that the cutting edge 5 becomes integral part of the respective die 7 or 8. Alternatively, the cutting device 4 may be also be designed as a separate component which is fastened on one of the two dies 7 or 8, (the top die 8 in FIG. 1), in a fixed position. As a third variant, the cutting device 4 may be arranged on one of the dies 7 or 8 so that it is adjustable in stroke relative to the respective die 7, 8.

When the cutting device 4 is integrated into one of the dies 7 or 8, the flange 3 can be cut off or severed in an especially powerful, and thus precise, manner, and the quality of a subsequent end product is therefore markedly increased. On the other hand, the embodiment of the cutting device 4 as a separate component which is fastened on one of the two dies 7 or 8 in a fixed position, offers the advantage that the cutting edge 5 (for example, a parting blade), can be exchanged in a simple and cost-effective manner. Hardened metals, for example, which have an especially long service life, are suitable as cutting edge 5. The third variant, in which the cutting device 4, with the cutting edge 5, is arranged in a displaceable manner on one of the dies 7 or 8, offers the advantage that the cutting operation can be separated from a closing operation of the tool 1, i.e. from a movement of the top die 8 and the bottom die 7 toward one another.

According to FIG. 1, a shaping die wall 17 is formed on a side 6 of the cutting device 4 facing the hollow profile 2, which bears against the die wall 17 after the cutting operation and during the subsequent internal high pressure forming. In this case, according to the illustrations in FIGS. 1 to 5, the top die 8 and the bottom die 7 each have an L-shaped cross section, such that, when they meet, the L-shaped portions form a cavity 14 in which the hollow profile 2 can be shaped by internal high pressure. The cavity 14 is in this case defined at least on one side by the die wall 17 of the cutting device 4.

As shown in FIG. 1 and FIG. 2, a positioning device 9 is provided on the tool 1. Before the cutting and forming operation, positioning device 9 presses the hollow profile 2 against that side 6 of the cutting device 4 which faces the hollow profile 2 (that is, against the die wall 17 of the cutting device 4). The positioning device 9 may be designed, for example, as a punch which is acted upon by spring force or hydraulic pressure and which is extendable and retractable in one of the dies 7 or 8, (the bottom die 7 in the drawings). In FIG. 2, the positioning device 9 is actuated and, in the actuated state, presses the hollow profile 2 against the side 6 of the cutting device 4.

At least one hold-down 10 is provided in the region of the cutting edge 5, and [[which]] fixes the flange 3 of the hollow profile 2 during the cutting operation. As illustrated in FIGS. 3 and 4, a second hold-down 10′ can also be provided by a stepped design of the cutting edge 5, to fix the hollow profile 2 in position during the forming operation or embossing and perforating operation following the cutting operation.

As also shown in FIG. 3, an embossing punch 11 is provided which is displaceable transversely to the longitudinal extent of the hollow profile 2 and provides an embossment (cf. FIG. 4) on the outside of the hollow profile 2 after the forming operation. The embossing punch 11 is preferably actuated hydraulically, and acts during the embossing against an internal high pressure p_(i) which prevails inside the hollow profile 2. The embossing punch 11 may expediently be arranged in such a way that it crosses and passes through the cutting device 4 in a corresponding opening 12 after the cutting operation and during the embossing operation. During the cutting operation, the embossing punch 11 moves with the cutting device 4 or the top die 8 transversely to its embossing direction. It is possible, for example, for an embossing surface 15 formed on the end face of the embossing punch 11 to be part of the shaping die wall 17 of the cutting device 4.

As mentioned above, the embossing of the hollow profile 2 is effected against the internal high pressure p_(i) and after the cutting operation, so that, with the embossing, an additional but facultative processing step can be carried out with the tool 1.

According to FIGS. 3 and 4, at least one perforating punch 13, which perforates the hollow profile 2 after the completed embossing operation, is disposed coaxially in the embossing punch 11. An embossing direction of the embossing punch 11 is in this case parallel to a direction of movement of the perforating punch 13. The tool according to the invention thus makes it possible to integrate a further likewise facultative processing step, namely the perforating of the hollow profile 2, into the tool 1 itself, so that the production process can be greatly rationalized.

In addition, the embossing or the perforating against the internal high pressure p_(i) offers the advantage that embossments produced beforehand are not adversely affected by the perforating or perforations on account of the internal high pressure p_(i), so that a high quality of the hollow profiles 2 produced can be achieved.

One possible method of cutting the hollow profile 2 or of forming, embossing and/or perforating the hollow profile 2 is to be briefly explained below:

As shown in FIG. 1, the hollow profile 2 (at this stage is still a hollow profile blank, not designated in any more detail) is inserted into the tool 1, with the two dies 7 and 8 being in the open state (that is, positioned at a distance from one another). Thereafter, as shown in FIG. 2, the positioning device 9 pushes the hollow profile 2 (still before the cutting and forming operation), against that side 6 of the cutting device 4 which faces the hollow profile 2 (that is against the die wall 17). During the positioning, the tool, according to FIG. 2, is still in a partly open state, so that a simple adjustment of the hollow profile 2 in the direction of the cutting device 4 is possible.

The cutting operation is effected after the positioning. To this end, according to FIG. 3, the top die 8 moves toward the bottom die 7 and cuts off the flange 3 of the hollow profile 2 by means of the cutting edge 5, situated at the front on the cutting device 4 in the direction of movement. During the cutting operation, at least one hold-down 10 arranged in the region of the cutting edge 5 fixes the flange 3 of the hollow profile 2. After the cutting operation has been completed, a second hold-down 10′ fixes the remaining flange stub of the hollow profile 2 and thus fixes the hollow profile 2 in its position. After the cutting operation, cutting scrap (not shown) falls through an ejection shaft 16, which according to FIGS. 1 to 5 runs out vertically in the bottom die 7 in the direction of movement of the cutting device 4.

As can be seen from FIGS. 2 and 3, the flange 3 is cut by the closing of the tool 1 (that is, by a movement of the top die 8 toward the bottom die 7). It is also possible in this case for the cutting operation to be effected only after the closing of the tool (that is, when the top die 8 bears against the bottom die 7), by a cutting device 4 which is adjustable in stroke and is designed, for example, as a separate component.

After completion of the cutting operation, the hollow profile blank 2′ is formed by internal high pressure forming and in the process changes in size and form in accordance with the illustration in FIG. 3. During the internal high pressure forming, the positioning device 9 is actively shifted back or passively thrust back to a corresponding extent. That is, the holding or positioning force of the positioning device 9 is significantly smaller than the forces which occur during the forming and which widen the hollow profile 2.

After forming of the hollow profile 2, an embossing punch 11, which is displaceable transversely to the longitudinal direction of the hollow profile 2 can make an embossment on the outside of the hollow profile 2 according to FIG. 4. Such an embossing operation is optionally selectable. Embossing is effected according to FIG. 4 by the embossing punch 11 moving transversely to the longitudinal extent of the hollow profile 2 through the opening 12 in the cutting device 4 and embossing a recess in an outer wall of the hollow profile 2 by means of the embossing surface 15 provided at the front in the embossing direction.

In addition (or as an alternative) to the embossing operation, a perforating punch 13 arranged coaxially in the embossing punch 11 can perforate the hollow profile 2 after the embossing operation has been completed. (See FIG. 4.) To this end, the perforating punch 13 travels transversely to the direction of movement of the cutting device 4 and parallel to the embossing direction of the embossing punch 11 and pierces an outer wall of the hollow profile 2. According to FIGS. 3 and 4, one perforating punch 13 is provided. However, it is also possible for a plurality of perforating punches 13 to be arranged. It is also conceivable for perforating to be effected without embossing of the hollow profile 2. On account of the embossing punch 11 or perforating punch 13 acting against the internal high pressure p_(i), it is possible to carry out both the embossing and the perforating on the hollow profile 2 without these processing steps adversely affecting one another as in a conventional method of production in a plurality of steps.

The embossing surface 15 of the embossing punch 11, being arranged by way of example in the opening 12 of the cutting device 4, may form part of the side 6 of the cutting device 4 which is designed as a shaping die wall 17. However, it is also conceivable for the opening 12 not to open until during an embossing or perforating operation and for it to be closed during the cutting operation or during the forming operation, so that the shaping die wall 17 is formed completely by that side 6 of the cutting device 4 which faces the hollow profile 2.

In FIG. 5, the tool 1 is opened after the cutting and forming, embossing and/or perforating operations by moving the top die 8 away from the bottom die 7. In the process, the embossing punch 11 and also the perforating punch 13 are retracted into the tool 1 or the cutting device 4 at least to such an extent that the two dies 7 and 8 can move apart without any problems and the hollow profile 2 can be removed from the tool 1.

In summary, the features of the invention can be characterized as follows:

A tool 1 which is designed for cutting a flange 3 of a hollow profile 2 and for forming the hollow profile 2 by an internal high pressure forming process, includes a cutting device 4 which has a cutting edge 5, runs parallel to the longitudinal extent and can be displaced in the transverse direction of the hollow profile 2. A side 6 of the cutting device facing the hollow profile 2 is designed as a shaping die wall 17, against which the hollow profile 2 bears during the internal high pressure forming after the cutting operation. The invention thus enables a plurality of processing steps to be combined, for example the trimming, the forming, the embossing and the perforating of the hollow profile 2, at one production station. With the tool 1 according to the invention, a plurality of processing steps hitherto separate from one another can be effected promptly and without removal of the hollow profile 2 from the tool 1. In addition, the processing steps of embossing and perforating can be carried out optionally, so that cutting of the flange 3 and subsequent forming and/or subsequent embossing and/or subsequent perforating can be carried out with the tool 1 according to the invention.

That provision of the side 6 of the cutting device 4 which is designed as a shaping die wall 17, permits multifunctional use of the cutting device 4, which can therefore be simple to realize from the design point of view and at the same time constitute an especially successful design solution. In addition, because the embossing punch 11 or perforating punch 13 acts against the internal high pressure p_(i), exact embossing or perforating of the hollow profile 2 can be achieved, during which the embossing and the perforating do not adversely affect one another. As result, an end product of high quality can be achieved.

The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof. 

1. A tool for cutting a flange on a hollow profile and for forming the hollow profile by an internal high pressure forming process, the tool having at least one cutting device which runs parallel to a longitudinal extent of the hollow profile, has a cutting edge and is displaceable transversely relative to the hollow profile; wherein: a side of the cutting device which faces the hollow profile is provided as a shaping die wall, against which the hollow profile bears at least during the internal high pressure forming; and a positioning device is provided which, before the cutting and forming operation, presses the hollow profile against that side of the cutting device which faces the hollow profile.
 2. The tool as claimed in claim 1, wherein the tool has a bottom die and a top die which are displaceable relative to one another.
 3. The tool as claimed in claim 2, wherein the cutting device is one of: integrated in one of the dies, with the cutting edge forming an integral part of the respective die; a separate component, fastened to one of the dies in a fixed position; and arranged movably on one of the dies in such a way as to be adjustable in stroke.
 4. The tool as claimed in claim 3, wherein: at least one hold-down is provided in the region of the cutting edge; and said at least one hold down fixes the flange of the hollow profile at least during the cutting operation.
 5. The tool as claimed in claim 4, further comprising an embossing punch; wherein: the embossing punch is displaceable transversely to the longitudinal extent of the hollow profile; and the embossing punch makes an embossment on the outside of the hollow profile after the forming operation.
 6. The tool as claimed in claim 5, wherein the embossing punch is arranged such that it crosses and passes through the cutting device in a corresponding opening during an embossing operation.
 7. The tool as claimed in claim 6, further comprising at least one perforating punch arranged coaxially in the embossing punch, wherein the this perforating punch perforates the hollow profile after the embossing operation has been completed.
 8. A method of cutting a hollow profile, in which a flange on the hollow profile is cut by a cutting device which runs parallel to a longitudinal extent of the hollow profile and has a cutting edge that is displaced transversely to the longitudinal extent of the hollow profile; wherein: before cutting and forming operation, a positioning device presses the hollow profile against a side of the cutting device which faces the hollow profile; after the cutting operation and during a subsequent internal high pressure forming of the hollowing profile, the hollow profile bears against the side of the cutting device which faces the hollow profile and which is designed as a shaping die wall.
 9. The method as claimed in claim 8, wherein at least one hold-down arranged in the region of the cutting edge fixes the flange of the hollow profile at least during the cutting operation.
 10. The method as claimed in claim 9, wherein the flange is cut by closing the tool.
 11. The method as claimed in claim 10, wherein an embossing punch which is displaceable transversely to the longitudinal extent of the hollow profile makes an embossment on the outside of the hollow profile after the forming operation.
 12. The method as claimed in claim 11, wherein the embossing punch crosses and passes through the cutting device during the embossing operation.
 13. The method as claimed in claim 12, wherein: at least one perforating punch is arranged in the embossing punch coaxially thereto; and the perforating punch perforates the hollow profile before or after the embossing operation. 